1. Field of the Invention
The present invention relates to a water stop structure and is particularly designed to prevent water penetration into an electronic control unit through clearances between strands of wires constituting a wire harness when the electronic control unit and devices are connected via the wire harness.
2. Description of the Related Art
With increasing technical advantages, various electronic control units are installed in automotive vehicles and motorcycles. The electronic control unit controls various devices such as an injector and an ignition coil device based on detection signals from various sensors such as an O2 sensor, a speed sensor and a knock sensor, and is connected to respective devices such as the above sensors, controllable devices and electrical components by a wire harness.
Depending on the length, arrangement path and the like of a wire harness, a wire harness W/H is divided into a unit-side wire harness W/H-1 to be connected to an electronic control unit 3 and a device-side wire harness W/H-2 to be connected to devices 4, and the electronic control unit 3 and the devices 4 are electrically connected in many cases by connecting a connector 1 mounted on an end of the unit-side wire harness W/H-1 and a connector 2 mounted on an end of the device-side wire harness W/H-2 as shown in FIG. 14.
Since the wire harness W/H provided between the electronic control unit 3 and the devices 4 is arranged through a water susceptible area subject to water such as rainwater in many cases, it is important to prevent water penetration into the interior of the electronic control unit 3.
On the other hand, the present applicant proposed a waterproof connector 5 as disclosed, for example, in Japanese Unexamined Patent Publication No. 2004-146181 as a connector to be mounted on an end of a wire harness. In the waterproof connector 5, a waterproof rubber plug 6 is closely mounted in a rear part of a housing as shown in FIG. 15. Water penetration into the interiors of the connectors 1, 2 from the outside can be prevented, for example, by using such a waterproof connector 5 as the connectors 1, 2 at the ends of the divided wire harnesses W/H-1, W/H-2.
However, also in the case of the wire harness connected to the electronic control unit and the wire harness W/H divided as shown in FIG. 14, if an insulation coating portion of the wire of the device-side wire harness W/H-2 is damaged, a part of the coating portion is peeled off or a crack reaches up to strands of the wire, water such as rainwater might penetrate to strands of the wire from the damaged part. In such a case, the water having penetrated to the strands might infiltrate through clearances between the strands by a capillary phenomenon and penetrate into the electronic control unit via a connection terminal portion.